avformat/hevc: fix mix of av_malloc() with free()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/hevc.c

@@ -1056,7 +1056,7 @@ int ff_hevc_annexb2mp4(AVIOContext *pb, const uint8_t *buf_in,
     }
 
 end:
-    free(start);
+    av_free(start);
     if (ps_count)
         *ps_count = num_ps;
     return ret;
@@ -1109,7 +1109,7 @@ int ff_hevc_annexb2mp4_buf(const uint8_t *buf_in, uint8_t **buf_out,
     *size = avio_close_dyn_buf(pb, buf_out);
 
 end:
-    free(start);
+    av_free(start);
     if (ps_count)
         *ps_count = num_ps;
     return ret;